Thrombosis and thrombolysis are maintained in delicate balance by a series of high regulated enzymatic reactions. The component enzymes are are largely serine proteases which are produced as needed from zymogens, inactive forms of the enzymes which circulate in the blood at relatively high concentrations. It has become increasingly clear that the active forms of the pro- and anti-coagulant enzymes may be useful for evaluating patients afflicted with or at risk for thrombosis-related disorders.
For example, epidemiologic studies have demonstrated that elevated levels of fibrinogen and factor VII are associated with an increased risk of coronary artery disease and stroke. Some investigators have differentiated between activated and unactivated factor VII and find that the level of activated factor VII is the better risk indicator. In addition, there is evidence which suggests that the subset of the population that develops atherosclerosis may have a form of thrombotic diathesis which might manifest itself in the form of a chronic increase in activation of the coagulation/fibrinolytic system. Thrombotic manifestations of atherosclerotic disease such as stroke and myocardial infarction represent the major causes of mortality in the western industrialized world.
Identifying and evaluating patients at risk for thrombotic disorders will require accurate measurement of plasma levels of active pro- and anti-coagulant factors of the coagulation/fibrinolytic system. The need for this capability will grow in years to come. Heart disease, stroke and the many other thrombosis-related disorders occur most frequently in the older segment of the population. With the rapid growth of the older cohort of our population, the capability to monitor the activation state of coagulation/fibrinolytic system will be of increasing clinical utility.